Twitter algorithm on GitHub: the-algorithm (2023) and x-algorithm (2026)

Q: Where is the Twitter algorithm on GitHub?

Two places. The 2023 Twitter release is twitter/the-algorithm, with models in twitter/the-algorithm-ml. The current X code is xai-org/x-algorithm, commit cb45b55 as of this page. For You order is home-mixer/candidatepipeline/phoenixcandidatepipeline.rs. Weights are home-mixer/params/param.rs. Visibility rules are visibility-filtering/rules/registry.rs.

Q: Is the Twitter algorithm open source?

Mostly. The ranking code is public on GitHub: twitter/the-algorithm since March 2023 and xai-org/x-algorithm for the current X feed. The xai-org/x-algorithm README says the Grox classifier prompts are not shipped, and the trained Phoenix weights are not in the checkout either.

Q: What is the difference between twitter/the-algorithm and xai-org/x-algorithm?

twitter/the-algorithm is the March 2023 Twitter release, built around services such as home-mixer, simclusters-ann, and visibilitylib, mostly in Scala and Java. xai-org/x-algorithm is the code X publishes for the For You feed today, with thunder/, phoenix/ retrieval and ranking, and the weights in home-mixer/params/param.rs. To check what affects reach now, read xai-org/x-algorithm.

Last updated 2026-10-21. “Twitter algorithm GitHub” points at two repositories. Twitter published twitter/the-algorithm in March 2023: the Twitter-era recommendation services, mostly Scala and Java, with the model code in twitter/the-algorithm-ml. The code behind the X For You feed in 2026 is xai-org/x-algorithm, and that is the repo this page maps. This walkthrough is commit cb45b55 (2026-10-09). It follows the repo README.md and the file citations in X_ALGORITHM_BOOST_PLAYBOOK.md. It is a map, not a second ranker.

What the README says the repo is

The For You feed is assembled per request. In-network posts come from thunder/. Out-of-network posts come from phoenix/ retrieval, simclusters/, and home-mixer/sources/popular_posts_source.rs. The same model ranks both. Phoenix reads the viewer’s recent engagements and predicts an action probability per post. Weights in the code blend those predictions. A separate blending pipeline adds ads, Who to Follow, and prompts, which the model does not rank.

Ranking sets order. Whether a post can be shown is visibility-filtering/.

Where to read each stage

Stage	Path the README and the playbook cite
Request order	`home-mixer/candidate_pipeline/phoenix_candidate_pipeline.rs`
Query hydration	`home-mixer/query_hydrators/`
In-network store	`thunder/`, caps in `thunder/config.rs`
Out-of-network retrieval	`phoenix/`, source `home-mixer/sources/phoenix_source.rs`
Clusters	`simclusters/`, source `home-mixer/sources/simclusters_source.rs`
Popular list	`home-mixer/sources/popular_posts_source.rs`
Pre-score filters	`home-mixer/filters/`
Weighted sum	`xai-value-model/scoring.rs`, defaults in `home-mixer/params/param.rs`
Served recompute	`vm-ranker/`, including `vm-ranker/dpp.rs` and `vm-ranker/params.rs`
Visibility	`visibility-filtering/rules/registry.rs`
Training code	`phoenix/` (Cargo workspace, `pyproject.toml`, `phoenix/QUICKSTART.md`)

Tweet Mixer and the SID source are in the tree and default off. The playbook records PhoenixMaxResults 1000, ThunderMaxResults 1200, top-50 selection, and a served RESULT_SIZE of 35. Those numbers are in How the X (Twitter) algorithm works.

What GitHub does not include

The README section “What’s not in this repo?” says the Grox classifier prompts are not shipped. The playbook repeats that: Jinja templates are loaded by name from grox/flows/ptos/prompts.py and grox/flows/upa/prompts.py, and the prompt bodies are absent. Trained Phoenix weights are also absent. A default of 0.0 on a head means off in the mirrored primary config, not “the head was deleted.”

phoenix/run_pipeline.py, the old demo that used favorite 1.0 and reply 0.5, is not in this commit. The August 13, 2026 README release replaced that demonstration model with training code and the published weights.

The string TweepCred does not appear in this commit. The account-scoring job that does exist is user-cred-v2/, covered on What is TweepCred.

How tweet-factory uses the repo

tweet-factory does not run this pipeline. src/rank/weights.ts copies the published probability weights and the negative heads, and tf generate multiplies those by an editorial strength. The GitHub tree remains the source for the coefficients. A browser pass over one draft is tweetfactory.sh/score.

FAQ

Where is the Twitter algorithm on GitHub?

Two places. The 2023 Twitter release is twitter/the-algorithm, with models in twitter/the-algorithm-ml. The current X code is xai-org/x-algorithm, commit cb45b55 as of this page. For You order is home-mixer/candidate_pipeline/phoenix_candidate_pipeline.rs. Weights are home-mixer/params/param.rs. Visibility rules are visibility-filtering/rules/registry.rs.

Is the Twitter algorithm open source?

Mostly. The ranking code is public on GitHub: twitter/the-algorithm since March 2023 and xai-org/x-algorithm for the current X feed. The xai-org/x-algorithm README says the Grox classifier prompts are not shipped, and the trained Phoenix weights are not in the checkout either.

What is the difference between twitter/the-algorithm and xai-org/x-algorithm?

twitter/the-algorithm is the March 2023 Twitter release, built around services such as home-mixer, simclusters-ann, and visibilitylib, mostly in Scala and Java. xai-org/x-algorithm is the code X publishes for the For You feed today, with thunder/, phoenix/ retrieval and ranking, and the weights in home-mixer/params/param.rs. To check what affects reach now, read xai-org/x-algorithm.

Can you run the whole ranker from the GitHub checkout?

The README says Phoenix is meant to be trainable end to end, with a quickstart and synthetic data. It also says other directories may omit build files. The Grox prompts and the trained production weights are not in the checkout, so a local Phoenix run is not a reproduction of the live For You score.